Pot for the manufacture of plate-glass and the method of making the same.



UNITED STATES PATENT OFFIQE. i

CHARLES H. KERR, OF TARENTUM, PENNSYLVANIA, ASSIGNOR TO PITTSBURGH PLATE GLASS COMPANY, A CORPORATION OF PENNSYLVANIA.

POT FOR THE MANUFACTURE OF PLATE-GLASS AND THE METHOD OF MAKING THE SAME.

No Drawing.

To all whom it may concern:

Be it known that I. CHARLES H. KERR, a citizen of the United States. residing at Tarentum. in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Pots forthe Manufacture of Plate-Glass'and the Method of Making the Same. of which the following is a specification.

The invention relates to the making of pots for plate glass making or walls for contactwith molten glass, and has for its object the improvement of the product as set forth in my Patent No. 1,217,956 issued Mch. 6, 1917.

By the use of the procedure of the present applications which involve the use of finely divided silica (preferably secured by a grinding process), it is possible to make a pot or wall, which is more durable in fur nace operations, which is less subject to losses during the forming and drying of the pot, and which gives a superior quality of glass than where ordinary relatively fine sand as it occurs in nature is used. It is also possible by the use of this exceedingly fine silica to utilize clays which it would be impossible to use with coarser sand or less finely divided silica audit is possible to use as pot clay, a great many of the refractory plastic clays.

In my pending application referred to, .05 of an inch in diameter for the grains of silica was specified as the limit for coarseness. My present improvement contemplates the use of material whose grains for the major part are not over .005 of an inch in diameter. A much larger amount of the silica can be used when it is or this finely divided character without any undue cracking of the pots during furnace operations or to a less extent in drying, as Would be the case with coarsersilica. As in the process of mypending application, the silica is very uniformly' mixed throughout the clay and the procedure as to the forming of the pots or other walls is substantially the same as that pursued where ordinary clay is used.

The procedure followed in securing the finely divided silica is to grind pure glass sand between flint balls in a tube mill, but any other means might be employed for grinding the sand, or ground quartzite rock,

or any other form of substantially pure Specification of Letters Patent.

Patented Sept. 10, 1918.

Application filed December 18, 1916. Serial No. 137,698.

silica, might be used in place of the sand.

It might also bepossible to use some of the Per cent. Per cent. Mesh. Hole. partial t Per P residue. residue. passmg I 0087 0. O 0. O 100. U 120 0043 1. 7 1. 7 98. 3 200 00265 4. 5 6. 2 93. 8

The foregoing is merely representative of the degree of fineness wlnch I have found to be desirable. The material undoubtedly may be ground still finer with equal or greater success.

' In some cases it may be desirable, to use a quantity of coarser silica with the finer silica as aboi e described. Such coarser material would be desirable in connection with clay which is otheiwvise so sticky as to be diificult to work. The addition of the coarser silica in addition to the finer silica in a case of this kind serves to reduce the stickiness, and serves to reduce the shrinkage of the mass, so that the pots will dry without cracking. There might also ,be necessity in some cases of using some of the coarser material to. regulate the expansion and contraction of the mass to withstand furnace operating conditions. While my invention contemplates the use of the fine material, only, in most cases, it also contemplates the use of some coarser silica as above indicated in those cases where the quality of the clay makes it desirable.

I have found that the exceedingly fine material as above described may be used in greater quantity than the coarser unground sand or silica of corresponding coarseness, the total amount which may be added in some cases running as high as 50% of the total mixture of clay and silica. The range which can be used to greatest advantage lies between 15% and 45%, but even below 1 css and as the summit I here found that the mixture containing finer silica. fuses at lower temperature nan a corresponding mixture in which. the ice is in a relatively coarse granular form, lowering of fusing point does not involve any practical or factory discdvantage. The finer silica also produces a, denser receptacle than the coarser silica, but this does notintrodi e objection from a preclicel operating icnsity gives greater durability to the pot. he pot produced by the fine silica mixture more durable than the coarse silica min re, the Washing away by the action of the being; slower and more uniform, and he gloss produced in the line silica pots so; er or to that produced in the coarse Slllkifi,

oo the tirecdom from stone, string and roan being more marked (What I claim is:

The process of making refractory for contact with molten glass which con in mixing unifornil through plastic 'tory clay a quantity of silica divided so finely that the major ortion consists of grains than .005 of an inch in (lisuiei'ier.

2. The process of making refractor u for Contact with molten glass which con in mixing uniformly through ula tor-y clay a quantity of so i V. finely that the major portion grains less than of an inch in di and a large part of which consists ()Ii' .0025 of an inch in diametet:

3. The process of making refractory i ior contact with molten glass which cm s .111 mixing uniformly through plastic rail-actory cle -x a quantity of silica divided so finely that 907?; of the silica consists crsins which are less than 305 of an inci diameter.

4. The process of :nelcino refractory TIfillS for contact With nohen which con" in mixing uniformly through plastic re tor-y clay :1 quantity of ground silica d so finely that the HliljOl portion consists of grznnswnich less than .0025 of an inch in diameter.

5. The process 0i" inching refractory wells c. ns- N" slanupcnit ituLl inc greater oil , 1" finely ut toe mj f rains less than .005 of an inch 111 dlznneter the quanrt of some added to the clay con- Ftiuting from to 13971 of the total mixmore The process of making refractory WfiLllS for contact with molten glass which consists in mixing un formly through plastic reimo tory clay a quantity of silica divided so finely that the major portion consists of grains less than .005 oi an inch in diameter, and a large part of which consists of grains less than U325 of an inch in diameter, the quantity oi silica added-to the clay constitilting from 30% to 50% of the total mixture.

7. The process of making refractory Walls for contact with molten glass which consists in nit-zin uniformly through plastic refractory clay a quantity of silica divided so finely h the major portion consists of grainsless of an inch in diameter,

the quent ty of silica added to the clay con- The process of melting refractory Walls for contact win. en en glass which coni in mixing uniformly through plastic rectory cle quantity of ground silica divided so finely that she msj or portion consists of grains which are less than .9025 of an inchin diameter, the quantity of silica added. to the clay constituting from 30% to 50% of the total inizdure;

9., A receptacle for the melting of formed by adding to plastic I'QflSIC JOYY clay and mixing uniformly therethrough a quantity of silica equal. to from to 50% of the total mixture, the. silica being divided major portion consists of CHARLES KERR,

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the commissioner oi Zretents,

the melting of 

